Preparation impermeable for roentgen rays.



UNITED STATES PATENT OFFICE.

OSCAR GROS, OF LEIPZIG, GERMANY.

PREPARATION IMPERMEABLE FOR RQENTGEN RAYS.

No Drawing.

Speciflcation of Letters Patent. I

Patented Sept. 13, 1910.

Application filer! June p9, 1910. Serial N6. 569,556.

- To. all whom it may concern:

Improvements Be it known that -I, Os'oan GRos, a subject of the German Emperor. and resident of Leipzig, in the Kingdom of Saxony, German Empire, have invented new and useful in [Preparations- Impermeable for Roentgen Rays, of which the following is a full, clear, and exact specification.- i

-As is well known Certain compounds im permeable for Roentgen rays, such as bismuth and thorium preparations, are used for fillingcavities of the body in order to make the same accessible for the examination with Roentgen rays. In many cases large-quantities are required for this pur pose. A'measure very often resorted to for avoidin" the. use,,of excessively largequantities o thepure materials consists in mix- ..'ing the compounds with other .indiifer'ent preparations insoluble in water and diluted acids, such as white bolus. Mixtures of this kind, however, do not yield uniform images by reason of the fact that the eflicient coinpoundsare not quite uniformly distributed in the bolus, and more especially for the reason that, when suspending the mixtures in water to enable themto be taken by the persons to be examined, disintegration of the components will veryoften take place in "co sequence of the'diiferences in the.

specifi gravities of the components. I have found that it is possible to avoid these difficulties by coating the substance used as the diluting agent with the compounds impermeablev for the Roentgen rays. This coating can be effected by evaporating a solution of a suitable salt, for instance a bismuth salt, such as subnitrate of bismuth, in acidulated water in the presence of the said diluting agent, for instance a silica compound, such as white bolus or kieselguhr.

and then rendering the said salt insoluble by calciiiatio i, orby precipitatingsuch salt from its solution in the presence of such diluting agent by means of a suitable substance such as soda-lye and then calcinating, the corresponding oxids being thus deposited on the in ifi'erent substances. In this manner I obtain the substance not readily permeable for the Roentgen rays in a state of fine and even subdivision, but remaining nevertheless impermeable for Roentgen rays and capable of producing. a very uniform shading on the plate.

lVhen manufacturing such preparations I proceed forinstance as follows: I dissolve 10 grams of subnitrate of bismuth in diluted nitric acid, and then add to the solution 100 grams of white bolusQ I then evaporate'the mixture to dryness and subject it to calcination until no nitrogen oxids escape any more.

When using in this example only such a quantity of nitric acid as will be sufficient for dissolving the subnitrate of bismuth a partial precipitation of the bismuth salt will already result from the addition ofi white bolus aloneh Instead of nitrate of. bismuth I may also employ nitrate of thorium, andinstead .of white bolus I may employ kieselguhr.

y Preparations such as above described will be foundto contain the bismuth and thorium in a shape in which it is insoluble and noncapable of being resorbed, and they will. yield an intense and uniform shading on the Roentgen plate. a

1. The hei'eindescribed composition of matterimpermeable-to Roentgen rays, consisting of a comminuted substance indifferent to animal fluids, said substance being coated with a metal compound impermeable to Roentgen rays. I

'2. The hereindesoribed composition .of

matter impermeable to Roentgen rays, con- 

